Ventilated lamp guard

ABSTRACT

A lamp guard with a substantially cylindrical, hollow body including a flaring, e.g., dome-like, upper portion; a hollow, substantially cylindrical coaxial neck on the domed portion; elongated, horizontal, circumferentially spaced, ventilating slots in the upper portion of the body; and longitudinally arcuate, curtain walls depending from the flaring portion radially inwardly of the respective slots and extending approximately the length of the respective slots and below the lower edges thereof.

United States Patent 11 1 Trevithick VENTILATED LAMP GUARD [75]Inventor: Tony Trevithick,Gurnee, Ill.

[73] Assignee: Daniel Woodhead Inc, Northbrook,

lll. a

22 Filed: on. 12, 1972 1211 Appl. No.: 296,805

[52] U.S. Cl 240/102 1R [5]] ..B02c17/20 [58] Field of Search 240/92,102 R, 153,

[56] References Cited UNITED STATES PATENTS 9/l929 Finkbeiner 240/102 X9/l97l Marasco et al. 240/102 Primary Examiner-Samuel S. MatthewsAssistant Examiner-Michael L. Gellner Attorney-Johnston, Root, OKeeffe,Keil, Thompson & Shurtleff [5 7] ABSTRACT A lamp guard with asubstantially cylindrical, hollow body including a flaring, e.g.,dome-like, upper portion; a hollow, substantially cylindrical coaxialneck on the domed portion; elongated, horizontal, circumferentiallyspaced, ventilating slots in the upper portion of the body; andlongitudinally arcuate, curtain walls depending from the flaring portionradially inwardly of the respective slots and extending approximatelythe length of the respective slots and below the lower edges thereof.

8 Claims, 5 Drawing Figures VENTILATED LAMP GUARD The invention hereinpertains to improvements in lamp guards preferably molded from atransparent or translucent, moldable, heat resistant, synthetic polymer.A number of different types of lamp guards are known in the art. Forexample, in U.S. Pat. No. 1,695,468 the guard is made of an elasticinsulating material having a rear portion which expands over andelastically clamps upona socket for the lamp bulb. The body portion ofthe lamp guard embodies longitudinally extending openings separated byintegral strips. Further well known types of lamp guard utilize metalwire cages of various shapes in which the lamp bulb is protectivelynested. Another type of lamp guard, as shown in US. Pat. No. 2,236,940,is made of a dielectric thermoplastic polymer and comprises a series ofspaced narrow strips forming an annular wall which protectivelysurrounds the lamp bulb. Still another type of lamp guard is describedin U.S. Pat. No. 3,609,348. The guard is made of a strong, rigid,preferably translucent or transparent polymer having a bell-like shapewith alamp-socket-receiving, cylindrical, coaxial neck. The upperportion of the guard is provided with heat ventilating holes or slots,the latter having upper edge portions which extend outwardly in a radialdirection so as to overhang the bottom, outer edges of the slots. Thisarrangement of the slot edges is for the purpose of blocking entry ofrain water into the slots when the lamp guard is in the uprightposition.

THE INVENTION HEREIN The invention herein concerns improvements in lampbulb guards of the type particularly adapted to be mounted and surroundthe'lamps of a light string consisting of a series of lamp sockets'whichare electrically interconnected byelectric wires or cables. These lightstrings have a number of industrial, commercial or domestic uses eitheras atemporary source of illumination or a relatively permanent source.Each lamp socket and its electricalconnectionsare housed in anelectrically insulatinghousingwhich may'be supported on a separate lineor cable or may be supported by the electrical wires or cablesthemselves. The housingfor purposes of the subject invention preferablyhas a downwardly extending, cylindrical neck surounding the lamp bulbsocket.

The lamp guards herein are characterized by a substantially cylindrical,hollow, preferably translucent or transparent body having aflaring,preferably dome-like upper portion. A hollow, substantially cylindrical,coaxial neck projects upwardly from the upper portion of the flaring ordome-like portion. The hollow body is adapted to fit about a lamp bulb;The hollow neckis adapted to fit about the downwardly projecting neck ofthe lamp bulb socket housing in amanner firmly but removably holding thelamp bulb guard on the neck.

In order to ventilate the lamp bulb guard and prevent a build up oflamp-generated heat within such guard, the upper portion thereof isprovided with heatventilating openings. These openings are preferably inthe form of a plurality of elongated, horizontal, circumferentiallyspaced, ventilating slots. Such slots respectively have near to, butradially inward thereof, a longitudinally arcuate, curtain walldepending from the upper portion of the lamp guard, e.g., the flaring ordome-like portion. The. curtain wallsrespectively extend approximatelythe length of the slot and desirably extend below the bottom edge of theslot. This arrangement and orientation of the curtain wall provides themost advantageous heat ventilation for the lamp guard while at the sametime preventing rain, particularly wind driven rain, from entering theslots and coming into contact with the thin, hot, glass envelope of thelamp bulb, which might then shatter or crack.

Preferably, the entire lamp guard, including its body, neck and curtainwalls, is made in the form of an integrally molded, light-transmittingpolymer, e.g., Lexan (trademark), an irradiation-stabilized,non-flammable, heat resistant polycarbonate resin or polymer. Therespective curtain walls are preferably slightly shorter than, but widerthan, the respective lengths and widths of their slots. The lower edgesof the curtain walls are bevelled'to a relatively sharp edge. Such sharpedge has the advantage of not accumulating water in the form of dropletsalong the edge, which might be blown off the edge and into contactwith'the hot lamp bulb envelope. The upper edges of the respectiveventilating slots preferably are located partly or entirely in theflaring or dome-like portion in order to make these slots as high aspossible in the lamp guard for most efficient heat ventilation. In sucharrangement, the upper edges of the respective slots have radially outeredge portions slightly radially inwardly of the radially inward edgeportions of the bottom edges of the respective slots.

The bottom edges preferably are bevelled edges sloping,

downwardly and radially outwardly from a relatively sharp, radiallyinward-edge.

THE DRAWINGS Preferred embodiments of the invention are illustrated inthe drawings wherein:

FIG. 1 is an exploded, perspective, fragmentary view of a light stringwith a lamp guard of the subject invention in exploded position relativeto the electrical and lamp bulb socket housing;

FIG. 2 is a fragmentary, enlarged, diametric section view of the lampguard of FIG. 1; 1

FIG. 3 is a view similar to FIG. 2 of the second embodiment of a lampguard of the invention;

FIG. 4 is a perspective, fragmentary, sectionview the lampguard ofFIGS.l and 2; and

FIG. 5 is a fragmentary, side elevation .of the lamp guard. I

THE ILLUSTRATED EMBODIMENTS Referring tothe drawings, FIG. 1 illustratesone lighting unit ina series of lighting units makingup the light string10. A separate cable, wire or rope 11' is used to suspend the lightstring. Eachlamp unitissuspendedby meansof a link or clip 12 slidably ornon-slidably positioned over the cable, wire-or rope 1-1 andthrough ahole in the ear 13 of thelamp sockethousing 14. The lamp sockethousingmay have any external-configuration. In the illustrated embodiment, itis a. box-like structure made. of or covered by a dielectric, insulatingmaterial. Electrical cables or wires 16 and 17 extend into opposite endsof the housing 14, inside of which they are connected electrically (notshown) to the threaded socket 21 for the lamp.

The threaded socket 21 is housed in a cylindrical projection 18depending downwardly from the housing 15'. Thisprojection 18 may beintegral with the box 15 and preferably comprises a dielectric,insulating sheath about the threaded socket 21. For purposes hereinafterdescribed, the cylindrical projectiong 18 is provided with a ring recess19 providing opposing ring lips 20.

The lamp bulb guard 25 is composed of a substantially cylindrical body26 having at its lower edge a reinforcing, ring rib 24. The upperportion of the lamp guard has a hollow, substantially cylindrical,coaxial neck 27, the upper edge 28 of which is bevelled to facilitatesliding of the neck portion 27 over the cylindrical projection 18.Intermediate the ends thereof, the neck portion 27 has a tapered ring 29providing a downwardly facing, circumferential, ring lip 30. Whenmounted on the cylindrical projection 18, the tapered ring 29 and itslip 30 are positioned within the ring recess 19. This lip 30 may abutagainst the lowermost of the two ring lips 20 of the cylindricalprojection 18, thereby preventing the lamp guard from accidentiallyslipping off of the socket housing 14. It is preferred that at least oneof the tapered ring 29 and its lip 30 or the projection 18 and its lowerlip 20 be made of yieldable, resilient material. In the illustratedembodiment of FIGS. 1, 2 and 4, the housing and its projection 18 aremade of an elastomer whereby lower lip will yield sufficiently to allowthe neck 27 and its tapered ring 29 to slide over the lower lip 20 ineither direction upon application of sufficient manual pressure for themounting and removal of the lamp guard onto and from the lamp sockethousing 14.

The upper portion 31 of the lamp guard housing between the neck portion27 and the substantially cylindrical body 26 has a flared configuration,which may take the form of a frusto cone or a dome-like shape. In theillustrated embodiment, the upper portion 31 has a dome-likeconfiguration which provides a transversely rounded shape at leastadjacent the peripheral edge of the upper portion 31.

The upper portion 31 and/or the upper part of the substantiallycylindrical body 26 is provided with a plurality of circumferentiallyspaced ventilating slots 32. For optimum ventilation, these slots arelongitudinally horizontal slots having an upper, longitudinal edge 33near the periphery of the dome-like upper portion 31 and a lower,longitudinal edge 35 either in the domelike portion 31 or in the upperpart cylindrical body 26.

[n this preferred location for the longitudinally horizontal slots 32,the radially outer edge 34 of the upper longitudinal edge 33 ispositioned slightly radially inwardly of the relatively sharp, radiallyinner edge 36 of the lower longitudinal edge 35 (FIGS. 2 and 3). Thelower longitudinal edges 35 preferably are bevelled edges 37 which slopedownwardly and radially outwardly from the relatively sharp, radiallyinward edge 36. In this arrangement, water which drips off the radiallyouter edge 34 is in part or entirely directed by the bevelled edge 37onto the outer surface of the substantially cylindrical portion 26.

Each of the longitudinal, horizontal slots 32 has a correspondingcurtain wall 38 located near to, but radially inwardly from therespective slot. The curtain walls 38 are longitudinally arcuate wallswhich depend from the upper portion of the lamp guard, e.g., from theflared or dome-like portion thereof. As can be seen in FIG. 5, thelength of the respective curtain walls is approximately the length oftheir respective slots 32. Such length can be slightly shorter than thelength of the slots 32 as shown in FIG. 5 to provide optimum heatventilation without sacrifice of the rain-protecting function of thecurtain walls. Wind driven rain drops which do not strike directlyagainst a curtain wall 38, but rather passes obliquely and directlythrough the opening and past the curtain wall at the side edges of theopening do not have any deleterious effect on the heated lamp bulbenvelope because such rain drops strike against and run down theinterior wall of the lamp guard rather than the lamp bulb envelope.

The bevelled bottom edge 39 of the respective curtain walls 38 providesa relatively sharp edge 40 along the bottom of curtain walls, on whichrain droplets will not accumulate. With a more blunt edge, rain strikingagainst and flowing down the radially outer face of the curtain wallscan accumulate as droplets along the blunt edge. Such droplets cansubsequently either be blown against or fall upon the hot lamp envelope.

The embodiment of FIG. 3 differs from the previously describedembodiment in the structure of its neck portion. Here the neck portion27a is provided with a plurality of vertically extending slits 41 whichsubdivide the upper part of the neck portion 27a into a plurality ofvertically extending fingers 42. The fingers 42 are radially flexible.The upper edges thereof are com posed of tapered ring segments 43, eachproviding a downwardly facing lip 44. The latter are adapted tosnap-interlock with a lip like the lower lip 20 of FIG. 1, which isusually provided at a higher position on a lamp socket housing like thelamp socket housing 18. See, for example, US. Pat. No. 3,609,348. Theradially flexible fingers permit the lamp guard of FIG. 3 to be mountedon lamp bulb socket housings which are relatively rigid and notnecessarily made of a yieldable, resilient material as is the projection18 of FIG. 1.

It is thought that the invention and its numerous attendant advantageswill be fully understood from the foregoing description, and it isobvious that numerous changes may be made in the form, construction andarrangement of the several parts without departing from the spirit orscope of the invention, or sacrificing any of its attendant advantages,the forms herein disclosed being preferred embodiments for the purposeof illustrating the invention.

The-invention is hereby claimed as follows:

1. A lamp bulb guard comprising a substantially cylindrical, hollow bodyadapted to house the lamp bulb therein and including a flared upperportion; elongated, horizontal, circumferentially spaced, ventilatingslots in the upper part of said body; and longitudinally arcuate,curtain walls depending from the flared portion near but radiallyinwardly of respective slots and extending approximately the length ofthe respective slots.

2. A lamp bulb guard as claimed in claim 1, said body, its flared upperportion, and the curtain walls being an integral molding of alight-transmitting, synthetic polymer.

3. A lamp bulb guard as claimed in claim 1, said curtain wallsrespectively being slightly shorter than and wider than the respectivelengths and widths of said slots.

4. A lamp bulb guard as claimed in claim 3, the lower edge portions ofsaid curtain walls being bevelled to a relatively sharp lower edge.

5. A lamp bulb guard as claimed in claim 1, the lower edge portions ofsaid curtain walls being bevelled to a relatively sharp lower edge.

6. A lamp bulb guard as claimed in claim 1, the upper edges ofrespective slots being in the periphery of the flared upper portion andhaving radially outer edge means having a plurality of downwardlyfacing, lamp bulb sockets at spaced intervals thereon, said socketsbeing in respective dielectric housings, and a lamp bulb guard asclaimed in claim 1 depending from each housing in protective,surrounding relationship to lamp bulbs mounted in their respectivesockets.

1. A lamp bulb guard comprising a substantially cylindrical, hollow bodyadapted to house the lamp bulb therein and including a flared upperportion; elongated, horizontal, circumferentially spaced, ventilatingslots in the upper part of said body; and longitudinally arcuate,curtain walls depending from the flared portion near but radiallyinwardly of respective slots and extending approximately the length ofthe respective slots.
 2. A lamp bulb guard as claimed in claim 1, saidbody, its flared upper portion, and the curtain walls being an integralmolding of a light-transmitting, synthetic polymer.
 3. A lamp bulb guardas claimed in claim 1, said curtain walls respectively being slightlyshorter than and wider than the respective lengths and widths of saidslots.
 4. A lamp bulb guard as claimed in claim 3, the lower edgeportions of said curtain walls being bevelled to a relatively sharplower edge.
 5. A lamp bulb guard as claimed in claim 1, the lower edgeportions of said curtain walls being bevelled to a relatively sharplower edge.
 6. A lamp bulb guard as claimed in claim 1, the upper edgesof respective slots being in the periphery of the flared upper portionand having radially outer edge portions located radially inwardly of theradially inner edge portions of the bottom edge portions of respectiveslots.
 7. A lamp bulb guard as claimed in claim 6, said bottom edgeportions being bevelled edges sloping downwardly and radially outwardlyfrom a relatively sharp, radially inward edge.
 8. A light stringembodying electrical cable or wire means having a plurality ofdownwardly facing, lamp bulb sockets at spaced intervals thereon, saidsockets being in respective dielectric housings, and a lamp bulb guardas claimed in claim 1 depending from each housing in protective,surrounding relationship to lamp bulbs mounted in their respectivesockets.